Note: Descriptions are shown in the official language in which they were submitted.
10bi~7Z7
BACKGROUND OF THE INVENTION
This invention relates to a process for producing alkynols by a
low pressure ethynylation reaction from an aldehyde and an acetylene in
the presence of a catalyst comprising a copper acetylide complex supported
on a transitional alumina carrier.
Alkynols are prepared in accordance with the well known pro-
cesses such as those described in United States Patent Nos. 2,232,867;
2,300,969; 2,487,006-9; 2,712,560; 2,768,215; 3,108,104; 3,294,849; and
3,560,576, viz., by reacting aldehydes with a~ acetylenic hydrocarbon of
the general formula RJC=~-H, wherein R represents hydrogen or the radical
of a hydrocarbon, such as methyl, vinyl, or phenyl. me acetylene or
acetylenic hydrocarbon is introduced into the reaction zone as a gas,
while the aldehyde can be a liquid under reaction conditions, or can be
present in a liquid solvent or diluent. Typically, the reaction involves
the reaction of acetylene and formaldehyde to yield butynediol and pro-
pargyl alcohol. It is known that the reaction proceeds at moderately
--2--
10t;8727
elevated temperatures of from 50 to 150 C. at superatmospheric pressures,
generally from 2 to 30 atmospheres. It has been stated to be desirable
to conduct the reaction at a pressure less than 10 atmospheres and with
careful temperature control to reduce the danger of explosion. Even at
these pressures, the acetylene gas has been diluted with inert gases or
vapors e.g., nitrogen, hydrogen or carbon dioxide in order to reduce the
danger of explosion. However, even under these conditions, the danger of
explosion still exists with the prior art processes.
The above-mentioned ethynylation reactions generally employ some
form of cuprous acetylide complex catalyst, either supported or unsup-
ported, which catalyst may be generated or made active by a variety of
methods and from a variety of copper compounds. Often they are used
together with a bismuth compound to minimize undesired cuprene formation,
minimizing undesired acetylene polymerization. Supported catalysts used
in the high pressure reaction systems are produced by impregnating the
support with a solution of bismuth and copper salts such as the nitrates,
drying and calcining to produce the metal oxides. The copper oxide
thereafter is converted to an acetylide complex in situ by suitable treat-
ment with acetylene and formaldehyde.
To achieve low ethynylation operating costs, it has been
preferred to use the supported catalyst in pellet form in a fixed bed,
plug flow process. Dilute aqueous formaldehyde and injection of acety-
lo6s~'~7
lene at relatively high pressure are employed to convert excess formalde-
hyde and minimize distillation requirements to produce a product of re-
quisite purity. However, this approach has necessitated high reactor
costs to permit use, not only at norma~ acetylene operating pressures of
up to 26 atmospheres, but also at the high pressures of up to 20 times
greater than normal which occur coincidentally with the occasional acety-
lene decomposition which occurs at high pressures.
It has been proposed to emp]oy such supported catalysts as
slurries in continuous agitated reactions. Hitherto in such systems,
however, not only has it been found necessary to remove and purify the
catalyst at frequent intervals to avoid fouling, but even with continuous
complete aatalyst purification and recycle, it has been necessary also
to operate at relatively low formaldehyde conversions and relatively high
acetylene pressures to achieve even marginally acceptable space/time
yields. Where such low pressure systems have been employed, the yield
and purity of product have not been sufficient to warrant commercial use
of such a system. Such processes have, heretofore, involved higher oper-
ating costs than fixed bed, plug flow processes because of the higher
product separation expense and have offered little in the way of savings
because of the relatively poor rate of reaction and inferior catalyst
life.
In general, it has been found, that unsupported active acetylide
catalysts prepared from cuprous compounds,
~06~'72'7
or from cupric compounds in such a way that a substantial portion
of the cupric compound is reduced to cuprous copper before
formation of the acetylide, tend to have a low carbon to copper
ratio in which condition, they have been described as being
in the form of small, sticky, relatively explosive particles,
commonly containing appreciable amounts of metallic copper.
Furthermore, it has been claimed in the literature that
generated cuprous acetylide complex catalysts prepared from
cupric compounds under an acetylene partial pressure of greater
than 2 atmospheres or in the absence of formaldehyde, or in
the presence of radically unbalanced amounts of acetylene or
formaldehyde, or from cupric compounds which are highly soluble
or dispersed in media where the compounds tend to dissolve,
tend to have an insufficient total surface area and are
accordingly not very effective, vis-a-vis, production of the
alkynol.
A catalyst based upon high surface copper carbonate
or certain other insoluble copper compounds has been described
(United States Patent No. 3,560,576) as one which obviates the
aforedescribed difficulties. It has been shown, however, that
such a catalyst is very sensitive and permanently loses
activity upon being starved for either formaldehyde or acetyl-
ene and, as pointed out therein, can easily be detonated by
heating to 162C.
A catalyst comprising a water-insoluble cuprous
acetylide complex catalyst supported on a magnesium silicate
carrier has been proposed. Such a catalyst provides substantial
~068~Z~
adYantages oYer the cuprous acetylide complex ethynylation
catalysts of the prior art such as those supported on carbon
or silica including its retention of activity for long periods
and its promotion of butynediol formation at an increased rate.
Even though this catalyst provides substantial advantages over
the other catalysts of the prior art, it has one disadvantage.
It has been found during use of the above cuprous
acetylide complex - magnesium silicate catalyst, that most of
the magnesia thereof is rapidly leached from the magnesium
silicate support, followed by a continuing slow dissolution of
silica therefrom such that, after the reaction has reached
equilibrium, about 200 ppm of dissolYed silica can be found in
the reaction medium. The magnesia and silica contaminate the
product and may cause difficulties in further processing. In
addition, this leached catalyst is relatively weak and tends
to break-up into fine particles under the normal mechanical
forces encountered while conducting the reaction. This causes
difficulties in separating the catalyst from the product
thereby resulting in increased cost of separation or in product
contamination.
It would be desirable to provide an ethynylation
catalyst which is active and selective for the conversion
of acetylene and an aldehyde to an alkynol and which is not
readily explosive, nor difficult to remove from the product nor
oyerly active in forming cuprene. Furthermore, it would be
desirable to provide such a catalyst which can be formed in situ
during the reaction and which promotes substantial reaction at
lower and safer acetylene reaction pressures. In addition,
~o~ z~
it would be desirable to provide such a catalyst having good
physical strength and which is not soluble in the reactants
or reaction products so that it can be used for long periods
without contaminating the product.
SUMMARY OF THE INVENTION
This invention provides (a) a particulate, water-
insoluble ethynylation catalyst comprising a cuprous acetylide
complex supported on a powdered transitional alumina carrier
as well as (b) a catalyst precursor comprising a reducible
copper oxide supported on a powdered transitional alumina
carrier. For purposes of this invention, (a) the cuprous
- acetylide complex is as defined in United States Patent No.
3,560,576, particularly as described in Column 3, lines 11-60,
and (b) the transitional alumina carriers described herein may
be defined as comprising nearly anhydrous aluminas having a
H2O/A12O3 mole ratio of about 0.02 to about 0.5 and a surface
area of at least about 10 m2/g, preferably greater than
25 m2/g, and most preferably about 100 to 500 m2/g. Such
transitional aluminas may be made from suitable sources thereof
such as alumina hydrates: alumina monohydrates, alumina
dihydrates, and alumina trihydrates; mixed alkali or alkaline
earth metal oxides - aluminum oxides such as Na2O llA12O3;
K2O-llA12O3; MgO-llA12O3; SrO-6A12O3; BaO-6A12O3; Li2O-5A12O3;
etc. Since the nomenclature is such in the alumina art that
there are many aluminas or hydrates thereof that are known by
several different names or synonyms, the following classifica-
tion of names and properties of aluminas - as contained in the
Kaiser Aluminum & Chemical Corporation, Kaiser Chemicals
Division publication on Specialty Aluminas, Section 1-5,
effective 9-1-72, relating to General Information, Properties
of Aluminas - is set forth.
-7-
10~ 7
_.___ . __ __
~ ~ ~ ~ ~ ~ ~ ~ O ~N u~ p,
¦ ,9 R ~j3 IR R p~ ~ ~ ~ N ~ R o ~D V ~ N~ l
h _ __~ ___ __.__ _ _ _.
I-- N N o_r ___ N N C~
O ~ h ~ ~ ~ ~B ~ 8
~4 ~ ~ N ~ N ~ N , ~ S~ 1-l
~!
-- N O o O o~l o
:~. _ _ ____ _~
3 ~: ~ u~ O N O
~1~ ~C~
O ~ Il~ . N u~ (y~ c0 .
~ ~ ~ ~ O~ Il~ O~ U~CO ~1 ~{) (r~
: co ~ N S N
U~,N ~ I/~oN ~ ~N ~
1:1 ~ U o O ~ h O
O, _.1
ON ^ O O O O N~ ~1
~N ? t~) H ~'i l I O
. . _ _ H _ ; _ ~
~ ~æ ~ ~ ~æ ..~ ~æ
g ~ ~
- 7a -
10~
._ _ . ~ .. _~_ ~ h 1
t~ ~ ~ h ~1 ~ h ~ Id
O O r~q~ U~ I a.) ~ a~ ~ p,~
h N t) t~q-l a ,_ c~ bC Fl~ ~ Pl h
c~ .~ P ~~14 1 ~, _, + ~ F4 +
~ æ ~ O ~ ~ ~ O ~ ~ ~ ~ ~ ~ ~ ~ ~ I ~
. _ .~ __ __ _ . I
~ ~ C~ ,1 ,1 a~ 01 ~ i,1
O __ h h _ ¦
u~ ~ 1 ~ l ~1
h ~ ~1 ~} h 'td h ~1 ~1 ~1 h ~1 C`~
,~0 'O P 'O P ~
~q ~h o ~ O U~
_ _
8 bD u~ g 8 $ o ~ o
~1l C'J 21 CU tr) I~ ~ ~1 1~
O 21 O O v 21 v V
__
U ~
~2 ~t ~O O C`J t~ C~J .
~ ~ ~10 (~ ~ tr~ t~) l ~
~ ~ C~i ~1
~ _ ~1 _
O n O
~_ ul ~ ~D ~
3 ~ 220 ~ O 1~ co i. i
~ ~ ~ ~On O 0~ _ _ 1--l Ct~ ~1
~ ~:1 C~C`J ~O ~ C`.l
O J ~ co ~
wn ~ ~ ~ _ _l _
; _ ~- ~2 _ ~ ~ _
i~ O -1 h ~ C~ o ~ u2 ~_ u ~ h~2 o C,~ o ~1
u2 ~ ~ ,o h rl 1: rl rl ~! - O 5: ,0 ~1 ~0
vh ~ 0~ ~ 21 3 v ~ .~ ~ v ~ v ~ o ~ o
_
~N r~ O U\ ~ N N N N N O
~ O O O O O O O O
0~ 21 2l ~ 21 ll 21 21 ~
h . n
~ _ . ~ ~
E~ ~ h ~ .. l ~ _~ æ
3 ~ ~3 ~ M ~ hl u~ ~! Cd ~ a 3 m ~ ~ ~ 3
1~ 01~ ~ 1~ il ~ Wl; v ~ cl~ ~ u ~ ~1 ~
- 7b -
10687;~7
___ __. ~ _. _
~ O h
~ o
:~J h rl U~ ~d
a ~o ~ ~ ~ ~
'a ~ ~ ~ ~ ~ a
~C~ ~ I ~ ~ o
O~1 ~1 'I ~ h
~ _____
a~ h ~rl
a~~ 1~ o o bO
,1 a
~ v v ~1 c~
cq ~ ~ ~
~ >~
rl ~o ~ o~ s~
a bD ~ ~) ~ a
~ô ~ o~
m cl ~1 N H
ca 'X ~I~ N ~0Ir~ O~
i~ ~ ~ o~ ~ ~ ~s~ o ~>
_~ ~ ~1 N O t-- ~ N^ ~rl t~
a a ~ 0~ ~^ ~ ~ ~ a
~ U~ ,,, ~
H C~ ~ ~ ~ G~ ~ 'h
E ~ u~ o ~) N ~O ~r)
~ 1~1~ "_~ - ~ / ~0 ,0 ~ ~
~ u O ~1 ~D q ~
~o~ ~ ~ ~ x ~ 3
O ~ N ~1 O
~N rO O O O a N U~
O O O~ 2; lQ
~N 11 11 11 ~ O
h ,~
~ ~î ~ ~
~ ~' ~ ~ ~ ~ ~a
~i 4¦ 4¦ ~ ~I h ~;
- 7C -
10687'~7
.
The catalyst precursor can be prepared by impregnating an unstable form of
a transitional alumina or a hydrated alumina with a copper salt and then
roasting the thus-impregnated alumina to convert the copper salt to copper
oxide and the unstable or hydrated alumina to a stable transitional alumina.
~he catalyst precursor also can be prepared by directly impregnating a
stable form of a transitional alumina with a copper salt followed by roast-
ing to convert the copper salt to copper oxide.
me catalyst and catalyst precursor also can contain bismuth,
which minimizes undesired cuprene formation without unacceptable effect on
alkynol production. The active catalyst is formed by contacting a catalyst
precursor in an 2queous formaldehyde medium at a temperature of about 70C
to about 120C, with acetylene, preferably at an acetylene pressure of less
than 2 atmospheres absolute pressure.
Ihe active catalyst is useful in forming alkynols from acetyl-
ene and an aldehyde, particularly formaldehyde, to form butynediol and
propar~yl alcohol.
Thus, this invention seeks to provide in a process for pre-
paring an acetylenic alcohol by reacting a lower aldehyde with acetylene at
about 60C to about 120C, the improvement which comprises effecting re-
action with acetylene at less than about 2 atmospheres partial pressure of
acetylene in the presence of an ethynylation catalyst comprising a water-
soluble cuprous acetylide complex and a stable transitional alumina powder
carrier therefor having a H20/A1203 mole ratio of about 0.02 to about 0.5
and a surface area of at least about 10 m2/g, said cuprous acetylide complex
being present in a concentration sufficient to catalyze the reaction of
said aldehyde and said acetylene to said acetylenic alcohol.
DESCRIPTION OF SPECIFIC EMBODIMENTS
This invention will be described hereinafter with reference
to the reaction of formaldehyde and acetylene. However, it is to be under~
stood that aldehyde reactants other than formaldehyde can be employed such
~ - 8 -
,.,
10687Z7
as acetaldehyde, proplonaldehyde, butyraldehyde or the like.
In a preferred embodiment of this inventlon, the catalyst
precursors of this invention are prepared by first impregn~ting an unstable
form of a transitional alumina or a hydrated alumina with a copper salt.
The impregnated alumina then is roasted at a temperature and for a time
- 8a -
~Of;~7Z7
as acetaldehyde, propionaldehyde, butyraldehyde or the like.
In a preferred embodiment of this invention, the catalyst pre-
cursors of this invention are prepared by first impregnating an unstable
form of a transitional alumina or a hydrated alumina with a copper salt.
The impregnated alumina then is roasted at a temperature and for a time
sufficient to convert the copper salt to copper oxide and to convert the
hydrated alumina or unstable transitional alumina to a stdble transitional
alumina. For purposes of this lnvention any unstable transitional alumina
that is useful herein is one which can be converted to a stable transi-
lo tional alumina during roasting from about 450 C to 600 C. for about 1 to
12 hours. A stable transitional alumina is one which will not be converted
to another alumina phase to a major extent under these conditions of time
and temperature. Representative unstable transitional aluminas are chi-
rho alumina and rho alumina, as defined above. Alternatively, the cata-
lyst precursor can be prepared by directly impregnating a stable transi-
tional alumina with a copper salt and then roasting the impregnated alumina
to convert the copper salt to copper oxide. It has been found that active
catalysts prepared from catalyst precursors formed from an unstable ~ransi-
tional alumina, particularly the chi-rho alumina, or a hydrated alumina
often exhibit greater activity than catalysts prepared from catalyst pre-
cursors formed initially from stable transitional aluminas. It is pre-
ferred to form the catalyst precursor initially from the chi-rho alumina
since the catalysts produced therefrom exhibit greater activity than many
catalysts produced from catalyst precursors formed initially from hydrated
aluminas or stable transitional aluminas. The alumina trihydrates, di-
hydrates or monohydrates per se, are unsuitable as the support for the
activated catalysts due to their lack of structural stability in hot
aqueous solutions and frequently inadequate surface area. The alpha phase
29 alumina also is unsuitable for use in this invention since it has a low
_g_
106~7Z7
surface area. Typical hydrated aluminas suitable for forming the cata-
lyst precursors of this invention include the trihydrates such as bayer-
ite, gibbsite or nordstandite; the dihydrates such as pseudoboehmite or a
monohydrate such as boehmite. The hydrated aluminas can be converted to
the transitional aluminas by dehydration as described hereinabove. As
noted above, the aluminas employed in this invention in forming the
catalyst precursor and/or the active catalysts can contain varying water
concentrations as follows:
Form of Alumina H20 : A1203, mole ratio
Trihydrate about 3.0
Dihydrate about 1.5 - 2.0
Monohydrate about 1.0 - 1.15
Rho about 0.5
Chi-Rho about 0.3
Usable Stable
Transitional Forms about 0.02 - 0.12
The active catalyst of this invention comprises a water-insoluble
powder comprising copper acetylide complex supported on a transitional-
alumina carrier therefor. Such catalyst contains between about 5 and
about 25 % by weight copper, and preferably between about 10 and about
15 % by weight copper, based upon the total weight thereof. me stable
transitional alumina carrier (of the active catalysts or employe~ to form
the catalyst precursor) may comprise partially dehydrated alumina powder
including gamma-alumina, eta-alumina, pseudogamma-alumina, kappa-alumina,
delta-alumina, and the like. The alumina employed herein as discussed
has a surface area per unit volume of at least about 10 m /gram, prefer-
ably greater than 25 m /gram, in order to promote high conversion of the
reactants to the desired produc~. The bulk density of the catalyst gen-
--10--
10t;~7'~7
erally ranges from about 0.4 to about 1.5 grams/cc. The catalyst of this
invention may contain bismuth in an amount of between 0 and about 5 % by
weight, based upon the total weight of catalyst in order to minimize un-
desired cuprene formation.
The catalyst of this invention provides substantial advantages
over the prior art cuprous acetylide complex catalysts employed to promote
the reaction of acetylene with formaldehyde. The catalysts of this inven-
tion are at least as active as those of the prior art for the formation
of alkynols. Unlike unsupported catalysts, such as those described in
United States 3,560,576, they are not explosive even when subjected to
severe shock and heat and thus are far safer than those of the prior art.
In addition, the active catalyst of this invention can be prepared in situ
during the formation of the alkynol at the preferred low acetylene partial
pressures of about 2 atmospheres or less. Furthermore, the catalysts of
this invention exhibit excellent stability including resistance to attri-
tion and insolubility of the carrier in the reaction products or reactants
encountered in the reaction system. Therefore, the catalysts of this in-
vention have a substantially improved useful life and need not be replaced
before they become deactivated. Furthermore, the catalysts of this inven-
tion can be separated easily from the product by physical means such as
filtration or centri~fugation and maintain this ease of separation. Also,
catalysts of this invention do not become permanently deactivated when
starved for either the f~rmaldehyde or acetylene reactant. As a result of
the improved characteristics of the catalysts of this invention, the alkynol
--11--
106~7Z7
product obtained from their use has little or no catalyst contamination
either from the catalyst, per se, or from soluble constituents or deriva-
tives of the catalysts and can be employed in a continuous or semi-continu-
ous process wherein the relative concentration of formaldehyde and acetylene
changes over ~he course of the reaction.
m e particle size of the resultant catalyst, while not in general
a fac~or that is critical to the successful practice of this invention, is
preferably small in size, preferably ranging from a particle size of be-
tween about 1 micron and about 1 mm so that the catalyst has a high surface
area and activity and can be separated easily from the liquid products.
In general, particle sizes below 1 micron are not preferred because they
are too small to be easily separated by conventional means, and particle
sizes above about 1 mm tend to give slower reaction rates and be more
difficult to pump and hence are likewise not preferred. Optionally, im-
pregnation can`be carried out with the addition of a bismuth salt to func-
tion as an inhibitor of acetylene polymerization activated by copper metal.
m e impregnated mixture is heated to drive off volatiles, convert any un-
stable aluminas to a stable transitional alumina, and to convert the salts
to the cupric oxide precursor of the active catalyst. Generally, the
desired conversion is carried out by heating the impregnated alumina at a
temperature between about 450 C and 600C, for a period from about 1 to
12 hours. Repeated tests have shown that the generated copper-impregnated
transitional alumina powdered catalyst of the instant invention cannot be
either detonated or burned, unlike unsupported copper-containing catalysts
-12-
1()~;~7Z~
of the prior art. Furthermore, the transitional alumina is insoluble in
the liquid reactants and products and is sufficiently strong as to with-
stand the mechanical forces normally encountered during the process.
The active catalyst is prepared by reduction of the cupric com-
pound to the cuprous compound by subjecting the catalyst precursor, in an
aqueous medium maintained at a temperature of about 70 C to about 120 C,
preferably to the simultaneous action of formaldehyde and acetylene at a
partial pressure of less than 2 atmospheres ~hereby generating the active
catalyst. Active catalyst generation and alkynol synthesis can go forward
continuously and simultaneously with the catalyst as a slurry in an aqueous
medium in a continuous stirred reactor at said temperature. As an alter-
native, however, one can first generate the catalyst in a separate reac-
tion zone and then place it in the ethynylation reaction zone where the
latter reaction can then be carried out. As a further alternative to
either of the aforesaid processes, the generated catalyst can be employed
(either manner of generation having been followed) until the activity
thereof drops below a desired point; at which time, the catalyst can ~hen
be replaced with fresh catalyst either by completely removing the former
or by withdrawing portions thereof while at the same time adding fresh
catalyst to the reaction medium.
In any case, in the generation procedure, the stable transitional
alumina impregnated with copper salt is reduced. The reduction of the
cupric compound and the subsequent production of aIkynol therewith can be
carried out in the same reactor, thereby forcing both the generation of
10687Z7
catalyst and alkynol product to be continuous and simultaneous at all
times. The cupric precursor is subjected in situ to the simultaneous
action of the reactants at the required pressure in a substantially aqueous
medium at the temperature of about 60 to 120C, preferably from 80 to
100 C. At temperatures substantially outside this range, or in strongly
basic or acidic media, or at low formaldehyde concentrations, or with an
inadequate supply of acetylene, poor catalyst tends to result. The pH of
the aqueous medium is in the range of 3 to 8 and preferably 4 to 7. The
concentration of f~rmaldehyde in the aqueous medium is preferably at least
6 % by weight. The ac~tylene partial pressure is in the range of 0.1 to
1.9 atmospheres; preferably it is in the range of 0.4 to 1.5.
In carrying out the catalyst generat on, nitrogen or another
substantially inert gas such as methane or carbon dioxide can be present,
as can also the common components of crude acetylene, such as ethylene.
Oxygen is preferably excluded for safety reasons. The supported cupric
precursor can be slurried in cold neutral formaldehyde solution and the
acetylene introduced before the slurry is heated. The aqueous solution
can advantageously be a stream containing propargyl alcohol and/or buty-
nediol, e.g., a recycle stream.
The catalyst generation reaction is preferably continued until
the cupric copper is substantially completely converted to the cuprous
acetylide complex, which with the preferred cupric precursors, generally
requires 1 to 24 hours after all the precursor has been contacted under
-14-
~0687Z7
the prescribed conditions. Preferably, also, the prescribed conditions of
temperature, pH and acetylene and formaldehyde concentrations will be
maintained throughout the catalyst generation. Activated catalyst also
can be prepared by incremental addition of make-up catalyst precursor
during a continuous process. However, departures from the prescribed
conditions during the course of the preparation reaction can be tolerated,
as the reaction is relatively insensitive to minor changes in operating
conditions.
The pH of the aqueous medium normally decreases as the reaction
proceeds, at a rate and to an extent which tends to increase with the
initial formaldehyde concentration, with the initial acidity of the reac-
tion medium and with the reaction temperature. Accordingly, the pH can
be, and advantageously is, controlled to some extent by beginning at the
preferred initial pH of 4 to 7, to some extent by operating in the pre-
ferred temperature range of 60 C to 120 C. Additional control can be
achieved by adding small amounts of acid acceptor such as sodium acetate
as the reaction proceeds. Further control can be achieved by carr~ing
out the catalyst generation as a continuous stirred reaction, while fresh
neutral formaldehyde solution is continuously introduced into an agitated
reaction zone as the reaction proceeds, and while maintaining the acetylene
partial pressure. During this step, any acidic effluent, if desired can
be filtered away from the copper-containing particles.
The ethynylation reaction per se, comprises contacting the reac-
tants at an acetylene partial pressure of not more than about 2 atmospheres
-15-
872'7
with an aqueous formaldehyde slurry of tne catalyst as above-described, in
a continuously stirred reaction at 80 C to 120C. m e formaldehyde and
acetylene are preferably continuously fed into the reaction zone where
they are introduced into and preferably below the surface of, the aqueous
catalyst slurry, and thoroughly mixed into the same by vigorous agitation,
and effluent is continuously withdrawn.
The reaction temperature for ethynylation is desirably 60 C to
120 C, advantageously 80 C to 115 C and preferably 85 C to 105 C. Advan-
tageously, the pH of the reaction mixture will be in the 3 to 8 and pre-
ferably 4 to 7 range, and can be maintained by ion exchange or acid
acceptor treatment of the continuous feed or by addition of asuitable
buffering agent.
m e formaldehyde concentration in the liquid medium in contact
with the slurried catalyst in the course of the ethynylation reaction will
be ordinarily 0.5 to 50 % by weight, under steady state conditions. Ad-
vantageously, the acetylene partial pressure will be in the range of 0.4
to 1.9 atmospheres. Preferably, the acetylene partial pressure above the
aqueous medium will be 0.5 to 1.5 atmospheres and the catalyst will be
present in amounts of about 1 to 25 weight parts per 100 weight parts of
aqueous medium. For the purpose of the present invention, in the substan-
tial absence of extraneous gas, the acetylene partial pressure can be taken
as the total pressure minus the absolute pressure of water and methanol,
formaldehyde, and propargyl alcohol, at the reaction temperature. As in
10687Z7
the catalyst generation, crude acetylene can be used, but for safety
reasons, it should be advantageously substantially free of oxygen.
The effluent from the reaction ~one can be heated in a still to
volatilize formaldehyde, propargyl alcohol and a portion of the water
which are condensed and combined with supplemental concentrated formalde-
hyde for recycle to the etnynylation reactor, purging any buildup of
methanol at convenient intervals in a continuous operation, and sending
the balance of effluent as aqueous butynediol directly to subsequent
treatment such as hydrogenation. Alternatively, effluent from the reac-
tion zone can be fed to a conventional plug flow ethynylation zone to
react any excess formaldeh~de.
In a particular embodiment of this invention, the reaction can
be carried out in a multi-stage reaction system wherein a mixture of the
catalyst, formaldehyde and acetylene are introduced into a first stage
at a relatively high formaldehyde concentration e.g. 30 % - 37 % by
weight, and thereafter passed, in admixture, to a plurality of downstream
reactors in sequence to obtain increased conversion of the formaldehyde.
The reaction mixture is removed from the last reactor and directed to a
gas-liquid separator wherein unreacted acetylene is separated from the
liquid reactants and products and the solid catalyst. rhe catalyst then
is separated from the reaction products and unconverted formaldehyde by
filtration, centrifugation or the like. The liquid obtained after cat-
alyst separation then may be distilled to separate unconverted formalde-
hyde from the alkynol product and to separate the butynediol product
from the propargyl alcohol. The separated catalyst and formaldehyde then
1068~27
are recycled to the first reaction stage. Make-up catalyst precursor may
be added to the first stage wherein the highest formaldehyde concentration
is maintained.
The invention will be more specifically described and explained
by means of the following examples, which are not to be considered as
limiting but merely illustrative of the invention. All parts and percen-
tages therein as well as in the appended claims are by weight unless other-
wise specified.
Example 1
This example illustrates the improved stability of the catalyst
of this invention against leaching by the reactants employed or products
obtained by the process of this invention.
m ree catalysts were prepared by mixing 100 g of a catalyst
support comprising respectively, kieselguhr, magnesium silicate or chi-rho
alumina with 100 ml of the following impregnation solution.
702 g. ( 3)2 3H20
102 g. Bi(N03)3-5H20
60 g. Conc. HN03
The impregnation solution was diluted to 1200 ml. total with water.
The impregnated supports were dried at 120-140 C. and then roasted
by slowly heating at a rate of about 50C. per hour and then maintaining
the roasting temperature at about 480 C. tor six hours to form a catalyst
precursor comprising copper and bismuth oxides impregnated on the support.
-18-
~0~;~7Z~
The catalysts were activated and used to react
formaldehyde and acetylene to form butynediol and propargyl
alcohol. Catalyst activation was carried out by stirring 100 g.
of the catalyst with 1 liter of a 35% aqueous solution o~f
formaldehyde at 80C. under an acetylene pressure of one
atmosphere. Activation was completed in 4 hours with the
kieselguhr and alumina and in 24 hours with the magnesium
silicate during which period, the catalysts became activated and
conversion to butynediol and propargyl alcohol was effected.
After activation, the catalysts were each used to ethynylate
one liter of 10% aqueous formaldehyde solution with acetylene
at one atmosphere pressure at 80C. for a period of 24 hours.
Upon completion of this reaction period, the catalysts
were each separated by filtration from the liquid reaction
medium comprising butynediol, propargyl alcohol and formaldehyde.
The recovered liquid reaction medium then was analyzed to
determine the amount of catalyst support solubilized in the
liquid reaction medium. The results are shown in Table I.
Table I
Catalyst Support Concentration in Liquid
Reaction Medium, ppm
A) Kieselguhr 100 (SiO2)
B) Magnesium Silicate 200 (SiO2) + some
magnesia
C) Chi-Rho Alumina (A123)
The initial unimpregnated chi-rho alumina (Kaiser
KA-300*) had a surface area of 350 m2/gram. On roasting, it
was converted to a mixture of eta and pseudogamma phase
* Trade Mark
-19-
10~ 7Z'7
aluminas. As shown in Table I, this a:Lumina support for the catalyst of
this invention is far less soluble in the liquid reaction medium than are
the kieselguhr or magnesium silicate supports. Furthermore, it was found
that the alumina-supported catalyst converted formaldehyde and acetylene
to butynediol at a rate similar to that obtained with the other two cat-
alysts but gave a ratio of propargyl alcohol to butynediol three times
that obtained with the magnesium silicate supported catalyst or kieselguhr
supported catalyst.
Example II
The active catalyst prepared from the chi-rho alumina by the
procedure of Example 1 was used to catalyze the reaction of acetylene and
formaldehyde.
Ten grams of the active catalyst was stirred with 500 ml of a
10 % aqueous formaldehyde solution at 80C for 50 hours. Thereafter, the
filtrate comprised 1.8 % formaldehyde, 10.9 % butynediol and 0.6 % pro-
pargyl alcohol.
Example III
This example illustrates a method for preparing the catalyst
precursor of this invention, activating the catalyst precursor and util-
izing the activated catalyst. A catalyst impregnating solution was pre-
pared by mixing:
880 g. Cu(N03)2 3H20
152 g. Bi(N03)3 5H20
75 g. Conc. HN03
Sufficient H20 to bring to 825 ml total volume.
After heating on a steam bath to complete solution, this solution
was milled to homogeneity with 1650 g. gamma
-20-
~a6~
alumina (Norton Company LA-6373*) having a surface area of about
250 m /gram. The impregnated alumina was separated by
filtration and then roasted under an air stream at 480C. for
about 6 hours. The product was a dark green powder, had a
surface area of 196 m2/gram, and assayed 12.5~ copper and
3.2~ bismuth.
Ten grams of the catalyst precursor thus obtained
was stirred with 500 ml. of a 35% aqueous solution of formalde-
hyde at 80C. under an acetylene pressure of one atmosphere for
6 hours. The mixture was cooled, the liquid withdrawn through
a filter stick and the catalyst sump used for a series of
ethynylations.
Ethynylation was carried out by mixing 10 grams of
the catalyst with 500 ml of a 10% aqueous formaldehyde solution,
while stirring, under an acetylene atmosphere at one atmosphere
pressure and heating the reactants, at 80C. for 50 hours.
Thereafter, the catalyst was separated by filtration and the
remaining liquid was analyzed and found to comprise 9.6~
butynediol, 0.5% propargyl alcohol and 2.8% formaldehyde.
Example IV
An activated copper acetylide catalyst, without
bismuth, was prepared by mixing:
880 g. Cu(NO3)2.3H2O
75 g. Conc. HNO3
300 ml. H2O
After heating on a steam bath to effect complete
solution, this solution was milled to homogeneity with 1650 g.
chi-rho alumina (Kaiser KA-300*) having a surface area of
* Trade Mark
~ -21-
.,~.
10~;~3727
about 350 m /gram and then roasted at about 480 to 500 C. for six hours.
The product was a dark green powder and assayed 13.0 % copper.
Ten grams of the catalyst precursor obtained was stirred with
500 ml of a 33 % aqueous solution of formaldehyde at 80 C. under an ace-
tylene atmosphere at atmospheric pressure for 6 hours. The mixture was
cooled and filtered to separate the activated catalyst from the liquid.
The separated catalyst was used to promote the reaction of form-
aldehyde and acetylene to butynediol and propargyl alcohol. Ten grams
of the cata]yst was mixed with 500 ml of a 10 % aqueous solution of
formaldehyde and stirred under acetylene at atmospheric pressure and was
heated at 80 C. for 50 hours. The catalyst and liquid then were separated
by filtration. The recovered liquid product comprised 11.8 % butynediol,
and 0.7 % propargyl alcohol and 1.1 % formaldehyde.
Example V
This example illustrates that copper acetylide catalysts sup-
ported on stable transitional aluminas can be prepared when employing a
hydrated alumina starting material.
To 100 grams of each of the hydrated alumina supports set forth
in Table II was added a solution comprising:
53 g. Cu(N03)2 3H20
9 g- Bi(N03)3 5H20
4.5 g. Conc. HN03
100 ml. H20
After heating on a steam bath to effect complete solution, the
resultant pastes were milled to homogeneity.
-22-
~Q6~372'7
The trihydrate pastes were then dried at 120 for 12 hours and then the
temperature raised at about 50 per hour to 480 C. and roasted at 480C.
in an air stream for 6 hours. The monohydrated alumina was treated sim-
ilarly except that it was roasted at a higher temperature (550 C). The
roasted aluminas were converted to transitional aluminas as shown in
Table II.
Table II
Transitional CuO, wt.
Catalyst Hydrated AluminaAlumina %
-
1 CX -Alumina Trihydrate chi 11.7
2 k3 -Alumina Trihydrate eta 12.1
3 oC -Alumina Monohydrate gamma 11.0
Each of the roasted, copper-containing catalysts was activated
by mixing 10 grams of the catalyst with 500 ml of a 35 % aqueous solution
ot formaldehyde stirred under acetylene at atmospheric pressure at a
temperature of 80 C. for 6 hours. The activated catalysts were re00vered
by filtration. The activity of the catalysts were determined by running
with 10 ~ aqueous formaldehyde for 50 hours at 80 C and atmospheric pres-
sure of acetylene. After reaction, the catalyst conversions were as
follows:
Catalyst Residual Formaldehyde _
1 3.5
2 3.7
3 2.0
Example VI
This example shows that the catalyst of this invention does not
permanently lose its activity in a reaction system containing a low con-
29centration of formaldehyde.
-23-
10~87;~7
Ten grams of the activated catalyst of Example lC was stirred
with 500 ml of a 20 % aqueous solution of formaldehyde under an acetylene
pressure of one atmosphere at 90 C for 6 hours. The catalyst was separ-
ated from the liquid reaction system by filtration. The reaction pro-
ceeded at a rate of 15 ml of acetylene consumed per minute. Thereafter,
the catalyst was exposed to a low concentration of formaldehyde by being
mixed with 500 ml of a 2 % aqueous solution of formaldehyde under an acety-
lene pressure of one atmosphere at 90 C. for 6 hours, giving a rate of 3
ml of acetylene consumed per minute. When this catalyst was re-admixed
with 500 ml of a 20 ~ aqueous solution of formaldehyde under an acetylene
pressure of one atmosphere at 90C., tne initial rate of reaction was only
9 ml of acetylene per minute for 6 hours. Upon once more repeating the
reaction with 20 % formaldehyde under the same conditions, the original
rate of 15 ml of acetylene per minute was res~ored.
Thus, the catalyst of this invention recovered its original acti-
vity and selectivity, as evidenced by the rates obtained even after having
been starved for formaldehyde under normal reaction conditions. This
example establishes that the catalysts of this invention can be employed
in a continuous process for converting acetylene and formaldehyde to
butynediol and propar!gyl alcohol even when starved for formaldehyde during
the process since the activity of the catalyst is shown to be restored
when subjected to normal reactant concentrations subsequent to formalde-
hyde starvation.
-24-
~06~7Z'7
Example VII
This example illustrates the use of this invention in a continuous
process.
A stainless steel stirred autoclave of one gallon working cap-
acity was charged with 500 grams of the catalyst of Example IV and 35
liters of 28 % formaldehyde solution. The reactor was purged wi~h acety-
lene and over a period of two hours the temperature was raised to 100C~
while the pressure was raised to 12 psig, continually passing fresh acety-
lene through the slurry.
When the operating conditions of 100 C and 12 psig were reached,
a steady addition of 0.7 liters of 28 % formaldehyde per hour was initiated
with the level in the reactor being mainta~ned by withdrawing product
steadily through an internal cartridge filter. After 20 hours the analyses
of the effluent solution stabilized and remained nearly constant. The
product contained 23.2 % butynediol, 1.8 % propargyl alcohol, and 8.3 %
residual formaldehyde.
-25-
